I've heard in the past that the idea that bananas are herbs was some horrible myth spread specifically by the Internet. Not true - I remember hearing it as a child, just like the idea that only an insane person could draw a perfect circle.

"Great," I thought, "now I can check this out properly," and went to google it. Almost nothing but the band, various "how to" pages, and something on a Terry Pratchett wiki, which came closest to providing a hint regarding the origin of the idea. I'll add this to my list of things to check in ten years' time (if both I and the Internet are still around), as sometimes these things take a while to get included (like Peterkin Custard).